Can't guarantee anything, but I think the PATH to the WTC and cab from there might be a good idea. There seem to be plenty of cabs down here. Caveat would be depending on time--closer it is to "rush hour", the more difficult it is to get cabs in Lower Manhattan.

If you had to come into NY Penn station, I think I read that the PATH is, for the duration of the strike, running trains on a loop from Penn out to Hoboken and into WTC, no transfers needed. I'd recommend double-checking my info, though.